fix(invest): mobile chart — fixed height, sane scales, horizontal x labels, compact legend/points, Chinese help

Root cause of the squashed chart: canvas had a fixed height=90 attr and no container, so on narrow viewports Chart.js compressed everything — legend overlapped the plot, x labels tilted 45deg, y ticks degenerated (-1000% scale). Fix: relative h-72/h-80 container + maintainAspectRatio:false, grace 5%, maxTicksLimit, maxRotation:0, smaller points (r2/1.5), compact legend/tooltip, Chinese help text.

invest/services.py

@@ -746,8 +746,8 @@ def _line_dataset(label: str, data: list, color: str, dashed: bool = False, widt
         'borderColor': color,
         'backgroundColor': color,
         'borderWidth': width,
-        'pointRadius': 4 if not dashed else 3,
-        'pointHoverRadius': 7 if not dashed else 5,
+        'pointRadius': 2 if not dashed else 1.5,
+        'pointHoverRadius': 4 if not dashed else 3,
         'tension': 0.3,
         'borderDash': [5, 5] if dashed else [],
         'fill': False,

invest/templates/invest/dashboard.html

@@ -125,7 +125,7 @@
     <div class="flex flex-col gap-3 lg:flex-row lg:items-center lg:justify-between mb-4">
         <div>
             <p class="text-xs font-semibold tracking-widest text-stone-500 uppercase">{{ fy_label }} Performance vs Benchmarks</p>
-            <p id="performanceChartHelp" class="text-xs text-stone-400 mt-1">Toggle between percentage return and dollar-value growth from the baseline date.</p>
+            <p id="performanceChartHelp" class="text-xs text-stone-400 mt-1">切换涨跌幅百分比与金额两种视图。</p>
         </div>
         <div class="flex flex-wrap items-center gap-2">
             <div class="inline-flex rounded-lg border border-stone-200 bg-stone-50 p-1 text-xs font-semibold" role="group" aria-label="Chart period">
@@ -142,7 +142,9 @@
             </div>
         </div>
     </div>
-    <canvas id="performanceChart" height="90"></canvas>
+    <div class="relative h-72 md:h-80">
+        <canvas id="performanceChart"></canvas>
+    </div>
 </div>
 {% endif %}
 
@@ -363,14 +365,32 @@
         const unit = currentData().unit;
         return {
             responsive: true,
+            maintainAspectRatio: false,
             interaction: { mode: 'index', intersect: false },
             plugins: {
-                legend: { position: 'top', align: 'start', labels: { usePointStyle: true, pointStyle: 'rect', pointStyleWidth: 14, padding: 20, font: { size: 12, weight: '600' } } },
-                tooltip: { callbacks: { label: function (ctx) { const v = ctx.parsed.y; if (v === null || v === undefined) return ctx.dataset.label + ': —'; return ctx.dataset.label + ': ' + (unit === 'currency' ? formatCurrency(v) : formatPercent(v)); } } },
+                legend: {
+                    position: 'top',
+                    align: 'start',
+                    labels: { usePointStyle: true, pointStyle: 'rect', pointStyleWidth: 10, padding: 10, boxWidth: 10, font: { size: 11, weight: '600' } },
+                },
+                tooltip: {
+                    position: 'nearest',
+                    padding: 8,
+                    titleFont: { size: 11 },
+                    bodyFont: { size: 10 },
+                    callbacks: { label: function (ctx) { const v = ctx.parsed.y; if (v === null || v === undefined) return ctx.dataset.label + ': —'; return ctx.dataset.label + ': ' + (unit === 'currency' ? formatCurrency(v) : formatPercent(v)); } },
+                },
             },
             scales: {
-                y: { ticks: { callback: function (v) { return unit === 'currency' ? formatCurrency(Number(v)) : formatPercent(Number(v)); }, font: { size: 11 } }, grid: { color: '#f5f5f4' } },
-                x: { grid: { display: false }, ticks: { font: { size: 11 } } },
+                y: {
+                    grace: '5%',
+                    ticks: { maxTicksLimit: 6, callback: function (v) { return unit === 'currency' ? formatCurrency(Number(v)) : formatPercent(Number(v)); }, font: { size: 10 } },
+                    grid: { color: '#f5f5f4' },
+                },
+                x: {
+                    grid: { display: false },
+                    ticks: { autoSkip: true, maxRotation: 0, maxTicksLimit: 8, font: { size: 10 } },
+                },
             },
         };
     }
@@ -386,10 +406,10 @@
         chart.options = chartOptions();
         chart.update();
         if (help) {
-            const baseline = currentData().baseline || 'the baseline date';
+            const baseline = currentData().baseline || '基准日';
             help.textContent = currentMode === 'value'
-                ? `Dollar mode: actual total portfolio value vs SPY/QQQ benchmark value from ${baseline}.`
-                : `Percentage mode: growth/decline since ${baseline}; cash-flow-adjusted metrics are shown in the cards above.`;
+                ? `金额视图：组合总市值 vs SPY/QQQ 基准（自 ${baseline}）`
+                : `涨跌幅视图：自 ${baseline} 以来的涨跌幅；卡片上方为现金流调整指标`;
         }
     }